hipple



Feb. 21, 1956 M. HIPPLE 2,735,405

HYDROELECTRIC CONTROL SYSTEM FOR HYDRAULIC APPARATUS Filed April 21, 1953 INVENTOR. GEORGE M. NIPPLE Y United States Patent HYDROELECTRIC CONTROL SYSTEM FOR HYDRAULIC APPARATUS George M. Hipple, Columbus, Ohio, assignor to The Denison Engineering Company, Columbus, Ohio, a corporation of Ohio Application April 21, 1953, Serial N 0. 350,024 6 Claims. (Cl. 121-38) This invention relates generally 'to hydraulics and is more particularly directed to .a control system for hydraulic apparatus. Still more particularly, the invention is directed to an electrical control system for hydraulic apparatus of the type having a reversible fluid motor.

An object of this invention is to provide an electrical control system for governing the operation of a reversible fluid motor of the type used, for example, in a hydraulic press, the motor being of the reciprocating piston and cylinder type.

A further object of the invention is to provide a control system for a reversible fluid motor, the system having a directional control valve with electro-responsive means for actuating such valve, the electro-responsive means being of the type which will cause the movable element of the directional control valve to move distances proportional to the current flowing through the electroresponsive means.

A still further object of the invention is to provide a control system of the type mentioned in the preceding paragraph, the system having an electric circuit for the eleetro-responsive means, the circuit including a plurality of current responsive relays and-variable resistance means actuated by the reversible fluid motor to effect the operation of the relay means.

Another object of the invention isto provide a control system of the type mentioned in the preceding paragraphs with a potentiometer having a plurality of resistance sections and means for adjusting the potentiometer to vary the resistance exercised thereby to control the relay means whereby the extent and rates of movement of an element of the reversible fluid motor will be controlled.

Still another object is to provide a control system of the type mentioned in the preceding paragraph with a connection between the movable element of the reversible fluid motor and the adjusting means of the potentiometer so *that the 'latter'will be adjusted as the motor is being operated whereby the movable element may be stopped and started automatically and 'the points at which the movable element is stopped and started varied through the adjustment of variable resistance means.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form of embodiment of the invention is clearly shown.

In the drawing:

The single figure is a diagrammatic view of a hydraulic press provided with an electric control system formed in accordance with the present invention.

Referring more particularly to the drawing, the numeral 20 designates the hydraulic section of the system.

This hydraulic section includes a fluid reservoir 21, a

reversible fluid motor 22 having a cylinder 23, a piston 24 mountedfor reciprocation in the cylinder, and aram 725 projecting from the piston. The system includes a pump 26, a relief valve 27 for limiting the pressure switches 68 generated in the system and a directional control or distributing valve 28. The valve 28 has a spool element 30 disposed for reciprocation therein, this spool serving to establish and interrupt communication between ports in the valve body. One of the ports, designated by the numeral 31, constitutes the inlet and is connected .by a line 32 with the pump 26, this line containing the relief valve 27. A line 33 extends from the relief valve to the reservoir to conduct fluid by-passed by the relief valve, when the pressure in the system exceeds a predetermined maximum, back to the reservoir. The body of valve .28 contains ports '34 and 35, the first of which is connected by a line 36 with the uper end of the cylinder 23 while port 35 is connected by line 37 with the lower end of this cylinder. The terms upper and lower ends are being used interchangeably with the terms forward and reverse, the latter terms designating the ends of the cylinders to which fluid is supplied 'to cause forward and reverse movement of the ram 25.

The parts of the hydraulic system are substantially conventional with the exception of the reversing or .dis- 'tributing valve which is provided with solenoids 38 and 40 connected with the spool 30 of the valve to move it in proportion to the amount of current flowing through the solenoids, the latter in this instance being of .the repulsion type, that is, 'when either of the solenoids is energized, the spool is moved away from the solenoid. By moving the spool distances proportional to the amount of current flowing through the solenoids, the rate of movement of the piston 24 and rarn 25 may be controlled.

The solenoids 38 and 40 are arranged in an electric control circuit which is designated generally in the draw iug by the numeral 41. This control circuit includes two portions, the first of which is a low voltage alternating current circuit while the second section is a higher voltage direct current circuit. The supply lines 'for'the alternating current circuit are designated by the numerals 42 and 43. The supply lines for the direct current section of thecircuit are indicated by the numerals 44 and 45. Each of the sections of the electric circuit includes aplurality of relays, the relays in the alternating current section being indicated by the numerals 46, 47, and 48. The relays in the direct current section are of the current sensitive type and are indicated by the numerals 50, 51, and 52. The direct current section of the circuit includes a potentiometer which, in this instance, has three resistance sections indicated by the numerals 53, 54, and "55, and three adjusting elements 56, 57, and 58. These adjusting elements are arranged to move along the resistance sections and are mechanically connected in any suitable manner, as indicated by dotted lines 60, with the ram 25 so that the elements will be moved in unison "with the ram. This movement of the elements 56 to 58, inclusive, varies the resistance exerted by the sections of the potentiometer in accordance with the movement of the ram. The elements 56, 57, and .58 are connected with variable resistors 61, 62, and 63, respectively, so that the potentiometer sections and the resistors will be arranged in series and their eliect will be cumulative. Resistors -61 to 63, inclusive, have selectively operable sliders 64 to 66, inclusive, by which the effect of the resistors may be varied. 'The purpose of this variable effect will be set forth in the following description.

The relays 46, 47, 48, 50, 51, and 52 are arranged to actuate a plurality of switches which are connected in different sections of the circuit for purposes which will be apparent also from the following description. Relay 46 might be termed the starting relay, the field coil of this relay being connected by lead 67 with line 43 of the alternating current supply. Lead .67 contains two and 70, the former being a normally open switch of the manually actuated type and constituting the starting switch. Switch 70 is a normally closed manually operated switch and constitutes the stop switch. It may be used for interrupting the operation of the system. When switch 68 is closed, current will flow to the field coil of the relay 46. When this coil is energized, it will effect the operation of two switch elements 71 and 72; switch 71 is arranged in a conductor 73, also containing a manually operated switch 74, leading from line 43 to conductor 67, this line and switch 74 being used when the device is set for the automatic repetition of the operating cycle of the hydraulic device. When only single cycle operation is desired, switch 74 will be maintained in an open position to render conductor 73 ineffective. When switch 74 is open, the closing of switch 71 will have no efiect.

Switch 72 is arranged in a conductor 75 which also contains a normally closed switch 76, this switch being a part of relay 50. Line 75 extends from supply conductor 43 to a line 77 containing another normally closed switch 78 forming a part of relay 51. This line 77 extends to the field coil of relay 47 which is also connected by a line 88 with the other conductor 42 of the alternating current supply. It will be obvious that, when the starting switch 68 is closed to energize relay 46, switch 72 will be actuated to close the circuit for relay 47, the current flowing from conductor 43 through line 75, switches 76 and 72, line 77, switch 78 to relay 47. When this relay is energized, three switches 81, 82 and 83 are operated. Switch 81, when closed, connects line 77 with conductor 43 and by-passes switches 72 and 76. Switch 82, when closed, connects solenoid 38 with the direct current supply lines 44 and 45 through conductors 84, 85 and 86, line 84 extending from direct current lead 45 to one side of the solenoid 38, line 85 connecting the other side of this solenoid with switch 82 and line 86 connecting this switch with the other direct current supply line 44. Line 86 contains a variable resistance device 87 which may be manually adjusted to vary the amount of current flowing to solenoid 38 and thus the degree of movement of reversing valve. Consequently the rate of flow of fluid to the motor 22 and the rate of movement of the ram 25 may also be regulated.

Quite frequently in the operation of hydraulic apparatus, particularly hydraulic presses, it is desired to cause a ram to move, during the first portion of its stroke, at a relatively rapid rate. By adjusting the resistor 87 to cause it to exercise slight resistance, a greater amount of current will be directed to the solenoid 38 causing the reversing valve to move a greater distance and permit more fluid to flow to the upper end of the cylinder 23. This larger volume of fluid will cause the ram to move at a relatively rapid rate. As the ram moves, the mechanical connection 60 between the ram and the elements 56 to 58, inclusive, of the potentiometer will cause these elements to move along the resistance sections 53 to 55. Resistance section 53 partially controls the flow of current to the relay 50. When the ram of the press or power cylinder 22 is retracted, element 56 is moved relative to resistance 53 to increase the resistance exercised thereby. This resistance will increase to such an extent that insufficient current will flow to relay 50 to effect its operation. The point in the retraction of the ram at which current flow to relay 50 is decreased enough to interrupt operation thereof may be varied through the adjustment of the slider 64. When the ram is being retracted and reaches this position, its movement will be interrupted in a manner to be described.

During the periods of inactivity of the power cylinder 22, the ram will be maintained in a retracted position. When it is desired to have the fluid motor perform a cycle of operation, the start switch 68 is closed as previously described. As soon as the flow of fluid to the upper end of the cylinder 23 is initiated, ram 25 will start to move in a forward or downward direction. This movement will be transmitted through the connection 60 to element 56 and the flow of sufficient current to effect the operation of relay 50 will be initiated. When the field coil of relay 50 is energized sufficiently, switch 76 will be moved to an open position and switch 79, also forming a part of relay 50, will be closed. Switch 76, as previously mentioned, is arranged in the circuit branch 75 containing field coil of relay 47 but, at this time, the opening of switch 76 will have no effect on the relay 47 since the portion of the circuit containing this switch has been by-passed by the closing of switch 81.

Movement of the ram 25 also effects movement of the element 57 relative to potentiometer resistance section 45. This resistance section, in cooperation with resistance 62, controls the flow of current to relay 51. The point in the movement of the ram at which resistance elements 54 and 62 provide sufiicient current flow to relay 51 to effect its operation will be determined by the position of the slider 65. When the ram reaches this point, relay 51 will be energized to operate switches 78 and 88. Switch 78 is a normally closed switch arranged in line 77 through which current flows to the relay 47. When relay 51 is energized, however, switch 78 will be opened thus interrupting current flow to the relay 47. When this relay is de-energized, switch 82, which partially controls the flow of current to solenoid 38, will be opened but solenoid 38 will remain energized by current flowing thereto over a second path comprising conductor 90 which contains a normally closed switch 91 and a variable resistor 92. Line 90 connects with line leading from solenoid 38 and contains the switch 88 which will be closed by the energization. of relay 51. Through the adjustment of the variable resistor 92 in line 90, the amount of current flowing to the solenoid 38 may be varied to cause the spool element 30 to move to a diflerent position whereby the rate of movement of ram 25 will be changed. As mentioned previously, the initial movement of the ram may be at a rapid rate then, when the ram reaches the point at which relay 51 is energized, the amount of current flowing to solenoid 38 may be decreased to cause the spool to reduce the amount of fluid flowing to cylinder 23 thus decreasing the rate of movement of the ram 25. If the same rate of movement is desired, the variable resistor 92 may be so positioned as to permit the flow of the same amount of current to solenoid 38 as was permitted by the resistor 87.

The ram will continue its movement at the reduced rate, assuming resistor 92 has been so set, until relay 52 is energized sufliciently to effect its operation. The point in the movement of the ram at which this operation will occur may be determined by the position of the slider 66 on resistor 63. Contact 58 of potentiometer section 55 also moves in unison with the ram 25. When the ram reaches the point at which potentiometer section 55 and resistor 63 establish sufficient current flow to relay 52 to eifect its operation, this relay will close switch 93. This switch is arranged in a conductor 95 which leads from one of the alternating current supply lines to the relay 48, this relay being connected by line 96 with the other alternating current supply line. Line 95 also contains the normally open switch 79, forming part of relay 50, and the normally closed switch 83, forming part of relay 47, which, with line 96, completes the circuit for relay 48 when relay 52 is energized and the operation of relay 48 actuates switches 91, 94 and 97. The former, as previously described, is arranged in line through which current is supplied to the solenoid 38. When relay 48 is energized, switch 91 will be opened to interrupt current flow to the solenoid 38 permitting the spool in reversing valve 28 to move to a position wherein inlet port 31 is blocked and flow of fluid to the cylinder 23 will be interrupted. The ram will then stop moving downwardly. Also when relay 48 is energized, switch 97 moves to a closed position completing a holding circuit through the portion of line containing switches 79 and 83 to the field coil of relay 48. This relay-will .remain energized until relay 47 is again energized to move switch 83 to an open position.

When relay 48 is energized. switch 94 is also moved to a closed position to complete a circuit for solenoid 4:). One side of this solenoid is connected with the source of direct current through line 84, switch 94 being connected with line 100 which extends from the other side of the solenoid. Switch 94 is also connected by a line 101 with the source of direct current, this line 101 containing a variable resistor 102. When switch 94 is closed, solenoid 40 will be energized to cause spool 39 to move in the opposite direction from which it was previously moved .thus connecting the source of fluid pressure with the lower end of the cylinder 23. The interruption of current flow to solenoid 38 and the establishment of current flow to solenoid 40 will occur substantially simultaneously. It should be obvious that, when either end of this cylinder is connected with the source of fluid pressure, the reversing valve also connects the opposite end of the cylinder with the reservoir so that fluid displaced by the piston 24 will be permitted to flow to the reservoir. When the lower end of the cylinder is connected with the source of fluid pressure, the piston and ram will be retracted. The rate of movement will depend upon the adjustment of the resistance 102.

When ram 25 is being retracted, the connection 60 will cause contacts 56 to 58, inclusive, to move in the opposite direction relative to their cooperating sections of the potentiometer. When the ram has been retracted to predetermined points, current flow to relays 5t 51 and 52 will be reduced to the extent that the switches associated there with will return to their normal condition. If switch 74 is open, the ram will come to rest in its retracted position when current flow to relay 50 is sufliciently reduced; to cause another cycle of operation of the ram, it will again be necessary to depress the starting switch 68. When a single cycle of operation is initiated, it is only necessary for the operator to retain the starting switch 68 in a closed position until relay 47 is energized then the starting switch may be opened and the cycle will be completed automatically. When it is desired to have the ram automatically repeat its cycle of operation, switch 74 is closed. Successive cycles will then be initiated at the termination of each cycle of operation by the closing of switch 76 forming a part of relay 50.

In some instances, it may be desirable to cause the downward or advancing movement of the ram to be interrupted when a predetermined pressure has been exerted thereby. To accomplish this operation, a switch 103, which will be closed in response to a predetermined pressure existing in the lines communicating with the upper end of the cylinder 23, completes a circuit containing the relay 52. This circuit will be placed in operation by the closing of a switch 104, which, in turn, disconnects section 55 of the potentiometer and resistor 63 from relay 52. This circuit branch controlled by the pressure switch 103 contains a resistance 105. It will be obvious that, when a predetermined pressure has been reached in the upper end of the power cylinder 23 causing the ram to exert a desired force, switch 103 will be closed. Relay 52 will then be energized, and in turn energize relay 48 through conductor 95, assuming that switches 79 and 83 are closed. The energizing of relay 48 opens switch 91 and interrupts the flow of current to solenoid 38 which causes the advancement of the ram and establishes current flow through the closed switch 94 to solenoid 40 which causes the retraction of the ram.

It will be obvious from the foregoing that an electric control system has been provided for hydraulic apparatus of the type having a reversible fluid motor, the control system serving to cause the fiuid motor to operate at a predetermined rate during an initial portion of cycle of operation then at a diiferent rate during the succeeding portion of the cycle of operation. The system will also con- "6 trol the points in the operating cycle of :the fluid motor at which operation will be interrupted and reversed.

While the form of embodiment of the present invention as herein disclosed constitutes a preferred form, :it is to be understood that other forms might "be adopted, all'coming within the scope o'f'the claims which follow:

I claim:

1. In a hydraulic deviceof the type having a reversible fluid motor and a source of fluid pressure, apparatus for controlling the flow of fluid from said pressure source :to said motor to govern the operationof the latter comprising a distributing valve between said fluid pressure source and said motor; electro-responsive means for actuating said distributing valve, said means being responsive in proportion to the current supplied thereto; an electric circuit .for said electro-responsive means; said-circuit having branches arranged for selective connection with saidelectro responsive valve actuating means, said branches supplying currents with different characteristics to said-electro-responsive means to secure different operations of :said valve and fluid motor; and means actuated by said fluid motor to connect said branches one at a time with said electroresponsive valve actuating means at predetermined stages of operation of said fluid motor.

2. In a hydraulic device of the type havinga reversible fluid motor and a source of fluid pressure, apparatus for controlling the flow of fluid from said pressure source =.to said motor to govern the operation of thelatter comprising a distributing valve between said fluid pressure source and said motor; electrowresponsive means for actuating said distributing valve to a degree proportional to the current flowing to said means; an electric circuit for said electroresponsive means; said circuit having .a plurality of branches arrangedfor selective connection .withsaid electro-responsive valve actuating means, selectively variable resistance means in certain of said branches to change the characteristics of current supplied :through such branches and secure different operations of said valve and fluid motor when different circuit branches are connected with said valve actuating means; and means actuated by said fluid motor at different stages of operation thereof to connect said branches one at a time with said electro-responsive valve actuating means.

3. In hydraulic apparatus of the type having a reversible fluid motor and a source of fluid pressure, apparatus for controlling the flow of fluid from said pressure source to said motor to govern the operation thereof comprising a directional control valve between said pressure source and said motor; electro-responsive means for actuating said valve to cause forward and reverse operation of said motor, said means being responsive in proportion to the current supplied thereto; an electric circuit for said electro-responsive means, said circuit having a plurality of branches arranged for selective connection with said electro-responsive valve actuating means, said branches supplying currents with diiferent characteristics to said electro-responsive means to secure different actions of said valve and fluid motor; electrical resistance elements mechanically actuated by said fluid motor to connect said branches one at a time with said electro-responsive valve actuating means; and additional resistance means connected in series with the first mentioned resistance elements to vary the stages in the operation of said fluid motor at which the different circuit branches are connected with said electro-responsive means.

4. In hydraulic apparatus of the type having a reversible fluid motor and a source of fiuid pressure, apparatus for controlling the flow of fluid from said pressure source to said motor to govern the operation thereof comprising a directional control valve between said pressure source and said motor; electro-responsive means for actuating said valve to cause forward and reverse operation of said motor, said means being responsive in proportion to the current supplied thereto; an electric circuit for said electroresponsive means, said circuit having a plurality of branches arranged for selective connection with said electro-responsive means, said branches supplying currents with different characteristics to said electroresponsive means to secure diiferent actions of said valve and fluid motor; means for connecting said branches one at a time to said electro-responsive means, said connecting means having a relay for each circuit branch; a potentiometer with a control section for each relay; a movable contactor for each potentiometer control section; and motion transmitting connection between a movable element of said motor and said movable contactors.

5. In hydraulic apparatus of the type having a reversible fluid motor and a source of fluid pressure, apparatus for controlling the flow of fluid from said pressuresource to said motor to govern the operation thereof comprising a directional control valve between said pressure source and said motor; electro-responsive means for actuating said valve to cause forward and reverse operation of said motor, said means being responsive in proportion to the current supplied thereto; an electric circuit for said electroresponsive means, said circuit having a plurality of branches arranged for selective connection with said electro-responsive means; means in said branches for selectively changing the characteristics of the current supplied through such branches and securing diflerent operations of said valve; means for connecting said branches one at a time to said electro-responsive means, said counecting means having a relay for each circuit branch; a potentiometer with a control section for each relay; a movable contactor for each potentiometer control section; a motion transmitting connection between a movable element of said motor and said movable contactors; and variable resistance elements in series with each control section of said potentiometer, the adjustment of said variable resistance elements varying the stages of operation of said fluid motor at which said relays are energized.

6. In a hydraulic device of the type having a reversible fluid motor and a source of fluid pressure, apparatus for controlling the flow of fluid from said pressure source to said motor to govern the operation of the latter comprising a distributing valve between said fluid pressure source and said motor; electro-responsive means for actuating said distributing valve, said means being responsive in proportion to the current supplied thereto; an electric circuit for said electro-responsive means, said circuit having a plurality of branches each of which has selectively variable means for changing the character of current supplied therethrough to the electro-responsive means to change the operation of said valve and motor; an electro-responsive switch means in each of said circuit branches; potentiometer means having a plurality of sections, each section being connected with and controlling a difierent electroresponsive switch means; an adjustable contactor for each potentiometer section; motion transmitting means connecting said adjustable contactors and a movable part of said fluid motor; selectively adjustable resistance elements in circuit with each potentiometer section to predeterminc the stage of operation of said fluid motor at which each circuit branch is connected with said electro-responsive valve actuating means; and relay means for initiating the operation of the control circuit and tie-energizing certain circuit branches when other circuit branches are energized.

References Cited in the tile of this patent UNITED STATES PATENTS 2,188,834 Fischel Jan. 30, 1940 2,262,173 Fischer Nov. 11, 1941 2,388,369 Shendrick Nov. 6, 1945 2,602,611 Glenny July 8, 1952 2,629,365 Kennedy Feb. 24, 1953 2,644,427 Sedgfield July 7, 1953 

